Recent Accounting Pronouncements	12 Months Ended
Dec. 31, 2018
Recent Accounting Pronouncements [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which amends FASB ASC Topic 606. ASU 2014-09 provides a single, comprehensive revenue recognition model for all contracts with customers. This standard contains principles for the determination of the measurement of revenue and the timing of when such revenue is recognized. Revenue recognition will reflect the transfer of goods or services to customers at an amount that is expected to be earned in exchange for those goods or services. In 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers: Deferral of Effective Date”, which deferred the effective date by one year to annual periods after December 15, 2017 including interim periods within that reporting period. In 2016, the FASB issued four additional ASUs related to Topic 606: ASU Nos. 2016-08, 2016-10, 2016-12 and 2016-20. These ASUs clarify various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations and licensing, and they include other improvements and practical expedients. The Company adopted this new standard on January 1, 2018 using the modified retrospective transition method, and has applied the provisions to contracts that were not complete as of January 1, 2018. Impact of Adoption The Company’s primary source of collaboration revenue has been through its license and collaboration agreements with three separate third-party licensees: Texas Institute for Genomic Medicine (“TIGM”), Sanofi and Ipsen. With respect to its contract with TIGM, the Company evaluated the variable consideration relating to the remaining milestone and determined, based on the most likely amount method, that it was not probable that a significant reversal would occur and therefore, concluded no constraint was required. Accordingly, the Company recorded a $14.2 million cumulative-effect adjustment to its accumulated deficit as of January 1, 2018 and reduced deferred revenue in the same amount. With respect to its collaboration agreements with Sanofi and Ipsen, the Company evaluated the variable consideration relating to future milestone payments and determined, based on the most likely amount method, that the estimated amounts could be considered as part of the transaction price. The Company then evaluated the variable constraint and determined that the variable consideration amounts are constrained, primarily by future events that are not within the control of the Company. The future events primarily relate to receipt of positive results from studies, approval from regulatory agencies, and upon achieving sales in certain locations. Accordingly, the Company determined that there was no cumulative adjustment required for these agreements on the date of adoption. The adoption of this ASU did not impact the timing or amount of revenues recognized related to its contracts with customers for the sale of product. In November 2018, the FASB issued ASU No. 2018-18, “Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606.” This targeted amendment to Topic 808 clarifies that certain transactions resulting from a collaboration agreement should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer for a good or service that is a distinct unit-of-account. This amendment is effective for fiscal years, and interim periods within years presented, beginning after December 15, 2019, and should be applied retrospectively to the date of initial application of Topic 606. The Company has applied the provisions of Topic 606 to account for its transactions for collaboration arrangements, including recognition, measurement, presentation and disclosure requirements. In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income. The pronouncement also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is not permitted. The adoption of this ASU on January 1, 2018 did not have an impact on Lexicon’s consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, “Leases.” ASU 2016-02 requires companies that lease assets to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The pronouncement will also require additional disclosures about the amount, timing and uncertainty of cash flows arising from leases. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. This ASU is required to be adopted using a modified retrospective approach. Management adopted ASU 2016-02 on the effective date of January 1, 2019. Upon adoption, the Company recognized $2.1 million for right-of-use assets and corresponding liabilities of the same amount on the consolidated balance sheet, primarily related to leases of office space. The adoption of this ASU on January 1, 2019 did not have a material impact on Lexicon’s consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, “Stock Compensation,” which is intended to simplify several aspects of the accounting for share-based payment award transactions. The Company adopted this pronouncement effective January 1, 2017. Upon adoption, the Company recognized approximately $6.1 million of accumulated excess tax benefits as deferred tax assets that under the previous guidance could not be recognized until the benefits were realized through a reduction in cash taxes paid. This part of the guidance is applied using a modified retrospective method with a cumulative-effect adjustment to the accumulated deficit for the excess tax benefits not previously recognized. However, given the full valuation allowance placed on the additional $6.1 million of deferred tax assets, the recognition of this provision of ASU 2016-09 had no impact to the Company’s accumulated deficit as of January 1, 2017. Additionally, the Company recorded an adjustment to accumulated deficit of $2.0 million as a result of making an entity-wide accounting policy election to account for forfeitures of share-based payment awards as they occur instead of estimating the number of awards that are expected to vest.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which amends FASB ASC Topic 606. ASU 2014-09 provides a single, comprehensive revenue recognition model for all contracts with customers. This standard contains principles for the determination of the measurement of revenue and the timing of when such revenue is recognized. Revenue recognition will reflect the transfer of goods or services to customers at an amount that is expected to be earned in exchange for those goods or services. In 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers: Deferral of Effective Date”, which deferred the effective date by one year to annual periods after December 15, 2017 including interim periods within that reporting period. In 2016, the FASB issued four additional ASUs related to Topic 606: ASU Nos. 2016-08, 2016-10, 2016-12 and 2016-20. These ASUs clarify various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations and licensing, and they include other improvements and practical expedients. The Company adopted this new standard on January 1, 2018 using the modified retrospective transition method, and has applied the provisions to contracts that were not complete as of January 1, 2018.

Impact of Adoption

The Company’s primary source of collaboration revenue has been through its license and collaboration agreements with three separate third-party licensees: Texas Institute for Genomic Medicine (“TIGM”), Sanofi and Ipsen. With respect to its contract with TIGM, the Company evaluated the variable consideration relating to the remaining milestone and determined, based on the most likely amount method, that it was not probable that a significant reversal would occur and therefore, concluded no constraint was required. Accordingly, the Company recorded a $14.2 million cumulative-effect adjustment to its accumulated deficit as of January 1, 2018 and reduced deferred revenue in the same amount.

With respect to its collaboration agreements with Sanofi and Ipsen, the Company evaluated the variable consideration relating to future milestone payments and determined, based on the most likely amount method, that the estimated amounts could be considered as part of the transaction price. The Company then evaluated the variable constraint and determined that the variable consideration amounts are constrained, primarily by future events that are not within the control of the Company. The future events primarily relate to receipt of positive results from studies, approval from regulatory agencies, and upon achieving sales in certain locations. Accordingly, the Company determined that there was no cumulative adjustment required for these agreements on the date of adoption.

The adoption of this ASU did not impact the timing or amount of revenues recognized related to its contracts with customers for the sale of product.

In November 2018, the FASB issued ASU No. 2018-18, “Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606.” This targeted amendment to Topic 808 clarifies that certain transactions resulting from a collaboration agreement should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer for a good or service that is a distinct unit-of-account. This amendment is effective for fiscal years, and interim periods within years presented, beginning after December 15, 2019, and should be applied retrospectively to the date of initial application of Topic 606. The Company has applied the provisions of Topic 606 to account for its transactions for collaboration arrangements, including recognition, measurement, presentation and disclosure requirements.

In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income. The pronouncement also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is not permitted. The adoption of this ASU on January 1, 2018 did not have an impact on Lexicon’s consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, “Leases.” ASU 2016-02 requires companies that lease assets to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The pronouncement will also require additional disclosures about the amount, timing and uncertainty of cash flows arising from leases. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. This ASU is required to be adopted using a modified retrospective approach. Management adopted ASU 2016-02 on the effective date of January 1, 2019. Upon adoption, the Company recognized $2.1 million for right-of-use assets and corresponding liabilities of the same amount on the consolidated balance sheet, primarily related to leases of office space. The adoption of this ASU on January 1, 2019 did not have a material impact on Lexicon’s consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, “Stock Compensation,” which is intended to simplify several aspects of the accounting for share-based payment award transactions. The Company adopted this pronouncement effective January 1, 2017. Upon adoption, the Company recognized approximately $6.1 million of accumulated excess tax benefits as deferred tax assets that under the previous guidance could not be recognized until the benefits were realized through a reduction in cash taxes paid. This part of the guidance is applied using a modified retrospective method with a cumulative-effect adjustment to the accumulated deficit for the excess tax benefits not previously recognized. However, given the full valuation allowance placed on the additional $6.1 million of deferred tax assets, the recognition of this provision of ASU 2016-09 had no impact to the Company’s accumulated deficit as of January 1, 2017. Additionally, the Company recorded an adjustment to accumulated deficit of $2.0 million as a result of making an entity-wide accounting policy election to account for forfeitures of share-based payment awards as they occur instead of estimating the number of awards that are expected to vest.